1. Field of the Invention
The present invention relates to a seat leg structure. More particularly, the present invention relates to a backward-leaning-movement seat leg structure.
2. Description of the Prior Art
An emergency landing or an improper landing by an aircraft can easily result in a strong shock and impact. If the aircraft shock-absorbing system can not entirely absorb the impact force, some impact energy will be transmitted to its structure and even to passengers inside. Therefore, airplane seats generally have an impact-absorbing function to protect passengers from injury.
U.S. Pat. No. 4,911,381 discloses an aircraft seat, as shown in FIG. 1, in which the numbers 100 and 200 respectively represent a seat portion and an energy absorber. Under a strong impact force, the aircraft seat legs rotate so that the seat portion 100 moves from position BC to position B.sub.1 C.sub.1. At the same time the energy absorber 200 extends and absorbs impact energy to protect the passenger.
However, research studies have shown that there is another potential danger. Under an impact force, the seat portion 100 rotates counterclockwise at an angle .alpha. and therefore leans forward. A passenger in the seat portion 100 also rotates counterclockwise so that his lap fails to obstruct his body from bending forward. In addition, the seat portion 100 moves forward in a horizontal displacement d. As a possible result, his head moves forward too much and collides against other objects.